A producer finds six dead calves among their 38-pair herd on pasture. These cattle have not been checked frequently, making the exact timelines of death unsure.
“A case of sudden death but we don’t actually know how sudden,” says Kansas State University Veterinarian Brad White.
In a December episode of Tox Talk, White and Scott Fritz, K-State clinical assistant professor of toxicology, discuss this unique case, unclear at first if it is a disease or toxin issue.
Diagnostic Timelines
Timelines are important to these aspects in an operation as Fritz explains there being a difference in, “they were alive and then dead suddenly or I suddenly found them and they’re all dead.”
Using decomposition rates to determine causes of death can be difficult, especially when they depend on season and temperature. In this case, the oldest dead calf is assumed to be 4 to 5 days old.
Depending on tests done, the decomposition rate may not affect results. However, 24 hours is typically the cut off for these kinds of tests on a corpse according to White. He explains it as “if you’re not going to gain much, it doesn’t make much sense to open them [corpses].”
Case Analysis
With calves aged 2 to 3 months, Fritz’s initial thoughts on the case are respiratory disease. White counters, saying that no clinical signs were shown, and it is odd that with this large a group of calves, there weren’t more affected. No cows were affected so, the case can be focused on issues that affect younger cattle.
Given this situation of acute death, clostridial diseases could be considered. But Fritz says it truly depends on vaccine history.
White brings up that Black Leg or overeating concerns are unlikely, especially with this many dying all at once.
A necropsy was performed with some of the fresher dead calves where veterinarians described the lungs as dark red, or purple and firm. It was noted that there were traces of tracheitis and bronchitis, and feces in the backside of the GI [gastrointestinal] tract were dry and firm.
Cranial ventral lung consolidation was described, and that is not typical of chronic respiratory disease. This does coincide better with tracheitis and acute death, which Fritz says he would then consider something more viral like IBR [Infectious Bovine Rhinotracheitis].
When looking at the lungs, test results showed an environmental contamination, which is not something typically seen with pneumonia.
Simply explained, the Histopath done showed dead cells, inflammation, no bugs and nothing on DNA diagnostics, as Fritz describes.
History of the herd is also a concern to look in to. There were no other clinical signs in the remaining 32 calves, nor any new introductions to the closed herd in this pasture from August to November.
All tests were negative, so Fritz takes this case a different direction to discuss toxins. Given these results, this is a Bronchopneumonia (BP) and not an Interstitial Pneumonia (IP).
This point limits a lot of inhalant factors.
The rumen content from the Histopath is where the case takes a turn. The contents in the sample bag smelled of petroleum, which is the diagnostic. This determines that it is an Inhalant Pneumonitis that the calves succumbed to, Fritz explains.
What Caused the Deaths?
The pasture contained a pump jack that moved mined product into storage tanks, which were fenced to contain spills. Calf hoof prints showed the calves accessed this fenced area and ingested contaminated soil or material. Although the contamination would have affected cows similarly, they were not impacted because they could not physically enter the contaminated area.
These products are classified by viscosity and volatility. More viscous substances, such as crude or mineral oil, pass through the GI tract with minimal symptoms, while more volatile products, like acetone, evaporate quickly, deeply penetrating lung tissue, and cause damage that is seen in this case. Fritz emphasizes that a product’s physical characteristics are critical to understand.
When testing for toxins like this, a fingerprinting test can be done where different spikes containing the source material are tested and matched to the rumen contents. But this is often expensive and challenging.
Fritz explains that the easiest way to test is to take the rumen content or feces, put it in a bucket with water and then the oil or petroleum contents will float to the top. Fritz notes that there are no diagnostic tests to show “this animal ate that,” so you must stack things together.
Key Take Away for Future Prevention
With an environment like this one, focus is often put more towards fencing and restricting the area. But Fritz explains it is also important to protect and isolate water sources from contamination like this to avoid further toxin issues in herds. It is important producers are aware of all the environmental factors their cattle face.
